@gargoyle67
The first thing I would do is to go into the linkss>screensaver folder and delete the blank screensaver that has been generated, then restart and then open a book that you have never opened before and that you 'know' the cover image works on....wait 20-30 sec, then go to sleep mode.
This will let you know if the hack is able to generate an image ...if there is already an image associated with a particular book (even a blank white one) the hack will not generate a new image of that book even if you delete and then reload the book to your PW. The hack does not delete old images files, you have to do that manually if you want that image gone.